v3.25.4
RESERVE FOR CLAIMS AND CLAIM EXPENSES - Schedule of Incurred and Paid Claims Development (Details) - USD ($)
$ in Thousands
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance $ 42,359,389                  
IBNR and ACR 14,348,345                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 24,326,113                  
Outstanding liabilities from accident year 2015 and prior, net of reinsurance 371,166                  
Adjustment for unallocated loss adjustment expenses 140,072                  
Unamortized fair value and other adjustments recorded in connection with acquisitions (142,082)                  
Liability for claims and claim expenses, net of reinsurance 18,402,432                  
Property                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 15,529,795                  
IBNR and ACR 3,038,508                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 10,669,725                  
Outstanding liabilities from accident year 2015 and prior, net of reinsurance 44,162                  
Adjustment for unallocated loss adjustment expenses 13,482                  
Unamortized fair value and other adjustments recorded in connection with acquisitions (34,312)                  
Liability for claims and claim expenses, net of reinsurance 4,883,402                  
Casualty and Specialty                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 26,829,594                  
IBNR and ACR 11,309,837                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 13,656,388                  
Outstanding liabilities from accident year 2015 and prior, net of reinsurance 327,004                  
Adjustment for unallocated loss adjustment expenses 126,590                  
Unamortized fair value and other adjustments recorded in connection with acquisitions (107,770)                  
Liability for claims and claim expenses, net of reinsurance 13,519,030                  
Accident Year 2016                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 1,795,946 $ 1,783,343 $ 1,778,053 $ 1,807,722 $ 1,777,006 $ 1,764,142 $ 1,844,016 $ 1,873,758 $ 1,914,267 $ 1,903,842
IBNR and ACR 25,759                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 1,699,007 1,674,337 1,635,307 1,606,372 1,541,169 1,435,839 1,298,756 1,119,951 907,718 471,704
Accident Year 2016 | Property                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 523,815 520,790 521,120 537,039 519,806 524,648 552,931 576,554 605,891 586,563
IBNR and ACR 2,839                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 487,249 488,731 486,340 489,700 484,239 474,232 447,535 413,532 330,698 145,590
Accident Year 2016 | Casualty and Specialty                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 1,272,131 1,262,553 1,256,933 1,270,683 1,257,200 1,239,494 1,291,085 1,297,204 1,308,376 1,317,279
IBNR and ACR 22,920                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 1,211,758 1,185,606 1,148,967 1,116,672 1,056,930 961,607 851,221 706,419 577,020 $ 326,114
Accident Year 2017                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 3,203,227 3,227,054 3,215,414 3,227,249 3,264,495 3,298,692 3,380,250 3,461,504 3,645,292  
IBNR and ACR 83,911                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 2,962,029 2,885,578 2,758,653 2,609,797 2,442,102 2,253,284 1,883,401 1,517,656 927,120  
Accident Year 2017 | Property                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 1,483,791 1,520,082 1,544,122 1,576,459 1,619,508 1,682,099 1,699,976 1,826,456 1,964,244  
IBNR and ACR 28,920                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 1,359,418 1,334,997 1,325,192 1,302,445 1,254,539 1,234,519 1,123,865 941,195 619,995  
Accident Year 2017 | Casualty and Specialty                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 1,719,436 1,706,972 1,671,292 1,650,790 1,644,987 1,616,593 1,680,274 1,635,048 1,681,048  
IBNR and ACR 54,991                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 1,602,611 1,550,581 1,433,461 1,307,352 1,187,563 1,018,765 759,536 576,461 $ 307,125  
Accident Year 2018                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 3,035,043 3,013,430 3,003,028 2,969,477 2,987,792 3,109,829 3,175,276 2,952,498    
IBNR and ACR 174,666                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 2,569,509 2,419,476 2,273,982 2,152,113 1,931,671 1,619,635 1,209,912 675,978    
Accident Year 2018 | Property                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 1,064,747 1,081,446 1,109,124 1,160,168 1,179,090 1,299,592 1,360,270 1,283,450    
IBNR and ACR 37,286                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 883,792 868,647 866,717 931,740 887,342 850,079 682,642 453,593    
Accident Year 2018 | Casualty and Specialty                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 1,970,296 1,931,984 1,893,904 1,809,309 1,808,702 1,810,237 1,815,006 1,669,048    
IBNR and ACR 137,380                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 1,685,717 1,550,829 1,407,265 1,220,373 1,044,329 769,556 527,270 $ 222,385    
Accident Year 2019                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 2,755,281 2,702,295 2,633,272 2,609,556 2,636,421 2,729,439 2,743,169      
IBNR and ACR 276,619                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 2,444,222 2,264,744 2,032,892 1,713,117 1,380,010 1,011,891 387,298      
Accident Year 2019 | Property                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 946,725 954,719 949,443 1,007,367 1,068,259 1,167,401 1,188,587      
IBNR and ACR 40,165                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 837,929 835,786 793,751 734,169 646,132 465,755 165,743      
Accident Year 2019 | Casualty and Specialty                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 1,808,556 1,747,576 1,683,829 1,602,189 1,568,162 1,562,038 1,554,582      
IBNR and ACR 236,454                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 1,606,293 1,428,958 1,239,141 978,948 733,878 546,136 $ 221,555      
Accident Year 2020                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 4,307,819 4,365,285 4,432,713 4,452,820 4,439,998 4,433,009        
IBNR and ACR 581,588                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 3,498,907 3,299,195 2,838,219 2,353,282 1,831,017 762,441        
Accident Year 2020 | Property                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 1,975,495 2,015,930 2,050,640 2,117,618 2,104,982 1,987,549        
IBNR and ACR 223,805                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 1,587,612 1,557,729 1,357,517 1,156,020 888,008 284,064        
Accident Year 2020 | Casualty and Specialty                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 2,332,324 2,349,355 2,382,073 2,335,202 2,335,016 2,445,460        
IBNR and ACR 357,783                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 1,911,295 1,741,466 1,480,702 1,197,262 943,009 $ 478,377        
Accident Year 2021                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 5,022,275 5,087,042 5,360,551 5,558,396 5,662,115          
IBNR and ACR 824,659                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 3,763,475 3,467,157 3,011,925 2,145,589 892,948          
Accident Year 2021 | Property                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 2,498,844 2,563,026 2,787,188 2,887,782 2,854,523          
IBNR and ACR 210,249                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 2,045,054 2,069,054 1,920,230 1,408,883 587,972          
Accident Year 2021 | Casualty and Specialty                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 2,523,431 2,524,016 2,573,363 2,670,614 2,807,592          
IBNR and ACR 614,410                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 1,718,421 1,398,103 1,091,695 736,706 $ 304,976          
Accident Year 2022                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 5,010,461 5,209,072 5,730,571 5,980,097            
IBNR and ACR 1,660,216                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 2,954,390 2,305,733 1,471,694 284,670            
Accident Year 2022 | Property                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 1,878,473 2,096,906 2,487,486 2,588,892            
IBNR and ACR 341,749                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 1,367,264 1,183,857 780,367 78,858            
Accident Year 2022 | Casualty and Specialty                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 3,131,988 3,112,166 3,243,085 3,391,205            
IBNR and ACR 1,318,467                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 1,587,126 1,121,876 691,327 $ 205,812            
Accident Year 2023                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 4,878,993 5,221,837 5,291,823              
IBNR and ACR 2,273,750                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 2,016,143 1,309,994 521,779              
Accident Year 2023 | Property                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 1,127,806 1,391,373 1,481,513              
IBNR and ACR 246,131                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 711,004 548,220 234,388              
Accident Year 2023 | Casualty and Specialty                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 3,751,187 3,830,464 3,810,310              
IBNR and ACR 2,027,619                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 1,305,139 761,774 $ 287,391              
Accident Year 2024                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 5,632,480 6,178,745                
IBNR and ACR 3,436,164                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 1,454,388 484,541                
Accident Year 2024 | Property                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 1,499,782 1,968,337                
IBNR and ACR 570,690                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 654,803 226,316                
Accident Year 2024 | Casualty and Specialty                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 4,132,698 4,210,408                
IBNR and ACR 2,865,474                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 799,585 $ 258,225                
Accident Year 2025                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 6,717,864                  
IBNR and ACR 5,011,013                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 964,043                  
Accident Year 2025 | Property                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 2,530,317                  
IBNR and ACR 1,336,674                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance 735,600                  
Accident Year 2025 | Casualty and Specialty                    
Claims Development [Line Items]                    
Incurred Claims and Claim Expenses, Net of Reinsurance 4,187,547                  
IBNR and ACR 3,674,339                  
Cumulative Paid Claims and Claim Expenses, Net of Reinsurance $ 228,443